<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding:0;
        }
        .nav{
            width: 1000px;
            margin: 0 auto;
            background-color: pink;
        }
        .nav::after{
            content: "";
            display: table;
            clear: both;
        }
        a{
            text-decoration: none;
            color: white;
            line-height: 40px;
            display: block;
            text-align: center;
        }
        li{
            list-style: none;
            float: left;
            width: 100px;
        }
        .drop-down{
            position: relative;
        }
        .drop-down:hover .drop-menu{
            background-color: deeppink;
            opacity: 0.5;
        }
        .drop-down:hover .hidden{
            display: block;
        }
        .hidden{
            width: 100px;
            position: absolute;
            background: deeppink;
            display: none;
        }
    </style>
</head>
<body>
        <ul class="nav">
            <li class="drop-down">
                <a href="#" class="drop-menu">收藏夹</a>
                <div class="hidden">
                    <a href="#">收藏宝贝</a>
                    <a href="#">收藏店铺</a>
                </div>
            </li>
            <li>
                <a href="#">卖家中心</a>
            </li>
            <li>
                <a href="#">联系客服</a>
            </li>
        </ul>
</body>
</html>